The objectives of the project are to identify and characterize Streptococcus mutans cell components that may exert detrimental effects on host tissue through direct interactions or by immunological mechanisms and to establish methodologies for the evaluation of future vaccines. One phase of the study will be concerned with antigens that are shared by S. mutant and human and monkey heart and kidney tissue (CR-antigens). CR-antigens (CR-50 and CR-24) will be extracted from S. mutans 10449 and purified using a variety of methods, including: gel filtration, isoelectric focusing, polyacrylamide disc gel electrophoresis and affinity chromatography. Groups of New Zealand white rabbits will be immunized with the purified bacterial antigens using intravenous and intradermal injections. Rabbit sera will be tested for antibodies to CR-antigens by indirect immunofluorescence (IIF), immunoelectrophoresis and indirect radioimmunoassay (IRIA). The effects of streptococcal induced tissue-reactive antibodies will be studied in actively and passively immunized rabbits. Resulting tissue pathology will be ascertained using both light and electron microscopy. Immunofluorescence, immunoenzyme, immunoferritin and conventional histological stains will be employed. The CR-antigen of animal tissue will be solubilized, purified, and biochemically and immunologically characterized. In a second study, other antigens of S. mutants 10449 cells will be tested for direct binding activities for heart and kidney tissue using IIF, IRIA and direct binding assays using radiolabeled bacterial components. The tissue-binding components (TB-antigens) and the tissue receptor will be isolated, purified, and characterized using the methods described above. The effects of the streptococcal TB-antigens (TB65, TB35) in vivo will be studied by injection of purified material into rabbits or by perfusion into isolated kidneys and hearts. Tissue pathology will be determined with the methods listed above.